#include<bits/stdc++.h>
using namespace std;
#define int long long
int  t,m,sz[101],w[101],zs[101][1001]; 
signed main(){
cin>>t>>m;
for(int i=1;i<=m;i++)
cin>>sz[i]>>w[i];
for(int i=1;i<=m;i++)
{
		if(sz[i]>t)continue;
				for(int j=t;j>=0;j--){
							zs[i][j]=zs[i-1][j];
				}
		
		for(int j=t;j>=sz[i];j--){

	
			zs[i][j]=max(zs[i][j],zs[i][j-sz[i]]+w[i]);
		//cout<<zs[i-1][j]<<" "<<i<<"  "<<j<<"  "<<j-sz[i]<<"  "<<w[i]<<" "<<	zs[i][j]<<endl; 
	
		}
	
}

	int ma=0;
	for(int i=1;i<=t;i++){
		ma=max(ma,zs[m][i]);
	}	
	cout<<ma;
}